/Engine/Source/Runtime/Core/Public/Templates/SharedPointer.h
Assignment operator adds a weak reference to the object referenced by the specified weak pointer. This assignment operator is intended to allow derived-to-base conversions.
template<typename OtherType, typename> [TWeakPtr](API\Runtime\Core\Templates\TWeakPtr) & operator= ( [TWeakPtr](API\Runtime\Core\Templates\TWeakPtr)< OtherType, Mode > const & InWeakPtr )